Ammonium nitrate in free-flowing form and method of preparing same



patented Nov. 4, 1952 um'ro sr AMMTfQNiU-M Ni'ifiiA'rE 1N FREEFLGWINGFORM AND METHOD OF PREPARING SAME john @Vhetstone, West Kiihride,seotiena", assignor to Imperial Chemical lndu stries Limited, acorptiiatifi of Great Britain No Drawing. Application July 12, 1949;Serial No. 104,389. In Great Britain April 26; 1949 Claims.

The present invention is concernedwith im vidingammonium nitrate in afree flow'ing form in whichthe tendency towards caking or' setting ofthe salt is much reduced and is an"improve= ment in or modification ofthe invention claimed mes-pending U. S; application Serial No. $0,439,filedJuly' 2'3; 1948, now abandoned, an application ofadditiontoco-pending U. S application" Serial No. 786F185; filedNovember 18; 1947', now abandoned, hereinafter referred to as the mainappli cation.

In said main application there is claimed a modifiedammonium nitrateconsistingef a mix ture of 100 parts of ammonium nitrate and 0.01 werepart of the mixtureof the sod um or ammonium salts of the'di--tri-sulpiiofii acids of para ros'aniline' and rosaniline commerciallyknowrr as thedyestuif Acid Magenta (Colour Inde'x" 692). It is Statedtherein that the quantit of Acid Magenta is preferably 005 to 0.10 partper 100- parts of ammonium nitrate.

In co-pending U.- S. application Serial No. 40,439, filed July 23, 1948itis stated that it has been found that certain dyestufis ofsulphonatedaromatic character, other than Acid' Magenta (No. 692") when distributedexternally in proportiorrof about 0.10% over the's'urfaces of ammom-umnitratein crystalline form or produced by a spray" crystallizationprecess, improve the resistance to caking" shown by the ammonium mtrate.

I-t'is alsdstatedthe'rein in" this connection that it has been foundthatcertain dyestuffs of sulphonated aromatic character other" than A'cidMagenta exercise an efiect on the crystal habit of ortho-rhombicammonium nitrate IV, which normally crystallizes as [110] prisms orneedles. It is further statedthat it has been found that the effect of agiven dyestuff onthe setting of ammonium nitrateis'linked with themagnitude of the crystal habit modification brought about on't-he-saltby a saturated solution of the dyestuff in-the saturated salt solution(mother liquor-'5 and that the solubility of the dyestuff in saturatedammonium nitrate solution atthe ordinary temperature is clearly animportant factorin deciding the-magnitude of the crystal habitmodification to be expected-but the number of the sulphonic acidsubstituent groups in the aromatic nucleus of the dyestufi are" alsovery important in conferring'sufiicient solubility'on the dyestufflFurthermore it is also remarked in said application of "addition U. S.application Serial No. 40,439 that asthe 'setting of ammonium nitrateappears to b essentially a" process of recrystal- 2 li'z'atiofi 6f theammo ium nitrate contained as' saturated solution the: moists alt, theeffect of a dyesturi' or" siilphonate'daromatic character on theofifst'al habit of the salt is likely to be refiect'ed iii its efieet'en the Setting of the salt, depending on the magnitude of the effectexerted on the rystalhabit and in general, w l 1en the presence of adyestue er; sulphonated aromatic chareater in t e erystalli'zinsolutio'nresults in the crystallization of the ammonium nitrate in the forin ofminute fragile scales or plates, a cons'iderame reduction in setting islikely to; he achieved, but the formation of bett er defined crystalforms is likely to reduce the efiect ofthe dyestuff' on setting ofammonium nitrate; It is further remarked therein the general effectofthese dyestuffs" ofsfilph'onated aromatic ch'aracter on the crystal ha'itof ammonium nitrate IV, is to induce"theforinationof [010] prismslaths,

plates of scales instead of the usual ii-0]- e1on-' gated prisms orneedles.

In accordance with the in ention claimed in x er al No. 40,439the-improveri ofthe invention of the sists in the erevis'ieii er amodified ammonium nitrate consisting o'f'a miiiture' of li l C l partsof ammonium nitrate and 0391 to t e r of at least one dyestflii" orsulplionated aromatic character,

other than Ab'id Magenta (No. 692) Which is soluble to the extent of atla'stlllOWZ- a saturated aqueous ammonium nitrate solution at ordinarya'tm'ospl'l'erie temperature: H v

It has" now" been found that particularly impreved results" are obtainedif the dyestufiof sulphon'ated arbmaue' character includedis one havinga solutmtydf not'le'ss than 0.5%; m a saturated" aqueous ammoniumnitrate solution at ordinary atmospheric temperatures'and preferablyf'is on which" has; ailiigher solubility than 0;5%; andif thedye'stu'fifof sulphonatedaromatic character is a soluble salt of apoly-sulphonatedderivative of a; diamin'o or"tria'mino substituted triarylmethanedyestufiora lower N-alkyl monoto tetra substituted compound ofany one such dyestuffi According to the present inven: the improvementin o'r modification of the venuon o'r s application Serial lie-46,439,the firstapplication of addition to themain Ii; application Serial No'.786,785; consists in the proyision' of a modified ammonium nitrateconsisting of' a mixture of parts ammoniumnitrate endoioor to parrot asoluble salt of a poly-sulphonated derivative of a diamino or "ontherefore triamino substituted triary1 methane dyestuff or a lowerN-alkyl monoto tetra-substituted compound of any one such dyestuff, saidpoly-sulphonated derivative having a solubility of at least 0.5% in asaturated aqueous ammonium nitrate solution at 20 C. and which insolution in a saturated aqueous solution of ammonium nitrate conditionssaid ammonium nitrate solution to produce on crystallization in thetemperature range in which the stable form of ammonium nitrate isammonium" nitrate IV crystals of ammonium nitrate IV as;[l0] prisms,laths, plates or scales and not as the usual [110] elongated prisms orneedles. 7

By the term lower alkyl is to be understood alkyl groups having up to 3carbon atoms.

, By the term aryl is to be understood simple monocyclic aromaticresidues particularly phenyl and tolyl.

It has to be understood that the modified ammonium nitrate can includemixtures of the sulphonated dyestuffs as hereinbefore defined, and ifdesired one or more of the said sulphonated dyestuffs can be inadmixture with Acid Magenta (No. 692). Ammonium nitrate modified by theadmixture of a mixture of the sodium or ammonium salts of the diortri-sulphonated acids of pararosaniline and rosaniline, which twodyestufis in admixture form Acid Magenta (N o. 692), forms the subjectmatter of our main application co -pending U. S. Application Serial No.786,785.

Typical dyestuffs which have been found to be eiiective are:

Tri-sulphona-ted pararosaniline (pp'p" triamino triphenyl methane)ammonium salt;

- Tri-sulphonated rosaniline (pp'p" triamino diphenyltolylm-ethane)ammonium salt;

Tri-sulphonated New Magenta (ppp" triamino tritolylmethane) ammonium orcalcium salt;

Tri-sulphonated p'p'p" triamino phenylditolylmethane, ammonium salt;

Red Violet RS (Rowe's Colour Index No. 693) which is a mixture of thesodium salts of diand tri-sulphonic acids of N -ethyl rosaniline;

Red Violet 4RS (sulphonated dimethyl rosaniline, Na salt) (R-owes ColourIndex 664).

Sulphonated diaminohydroxy triphenylsmethane (prepared by diazotisationand hydrolysis of one NH2 group of sulphonated p-rosaniline).

Trisulphonated monomethyl triamino tritolylmethane, sodium salt.

Ammonium nitrate according to the invention can be formed by directcrystallization from a solution containing at least one of thesaid'dyestuffs or while undergoing crystallization or granulation in forexample a graining kettle or incor-v porator in the presence ofsufiicient quantity of any one or more of said dyestuffs as hereinbeforedefined.

The addition of for instance 0.001 to 1.0 part in. solution or 0.1 to 1part in the dry condition of any one or more of said dyestuiis as hereinbefore defined to 100 parts of spray crystallized ammonium nitrate alsolessens the tendency towards caking or setting. Ammonium nitrate canalso be sprayed with a liquid containing the said dyestuff in aqueoussolution. Ammonium nitrate can also be treated with a solution of saidsulphonated derivative of a diamino or triamino substituted triary1methane dyestuff as herein'before defined in liquid ammonia or Diver'sLiquid and subsequently evaporating the liquid ammonia. The saiddyestuii can also be applied when absorbed in an absorbing material suchas kieselguhr. v

4 Ammonium nitrate modified according to the invention has been found tobe particularly suitable for incorporation in explosive compositions.

The following examples illustrate how ammonium nitrate according to thepresent invention can be produced. The parts are parts by weight.

' Example 1 Ammonium nitrate granules produced by a spraycrystallization process of particle size 30 to 100 B. S. S. are treated,with a solution of triamino tritolylmethane tri-sulphonate, ammoniumsalt, in liquid ammonia so that 0.03% of the dyestuii remains on thegranules of ammonium nitrate after the evaporation of the ammonia. Thecolour of the dyestufi does not appear until the ammonia is removed. Theammonium nitrate preserves" the original form of the granules and isfree running and resistant to setting.

Example 3 Ammonium nitrate is produced containing 0.05% of the dyestuffused in Examples 1 and 2 by the application of the said dyestuif as asolution in a mixture of '75 parts ammonium nitrate and 25 parts liquidammonia (Divers Liquid). The colour of the dyestufi does not appearuntil the ammonia is removed. The modified ammonium nitrate has theoriginal form of the granules and is free running and resistant tosetting.

Example 4' 5 parts of the dyestuff used in Examples 1 to 3 are dissolvedin hot water and mixed with parts kieselguhr and the mixture dried.parts of ammonium nitrate granules as used in Examples 1 to 3 areadmixed with 1. part of the thus treated kieselguhr. When the ammoniumnitrate absorbs moisture the dye .is leached out by the surface'film ofsaturated solution produced. The treated kieselguhr also improves the-free running qualities of the ammonium nitrate-which is renderedresistant to setting by the dye treatment.

Example 5 The surfaces of ammonium nitrate granules produced by a' spraycrystallizationprocess, of particl size 10-30 B. S. S., are treated witha 10% aqueous solution of triamino triphenyl methane trisulphonate,ammonium salt, so that the modified ammonium nitrate contains 0.009% ofthe dyestuff. The granules are dried and the dry product preserves theoriginal form of the granules, andthe free running qualitiesand'particularly the resistance to caking are improved.

ExampZe'G The moist crystals of ammonium nitrate, produced directly fromaqueous solution, are treated with .05 of triamino tritolylmethanetrisulphonate, ammonium salt, either dry or in aqueous solution, and theproduct is passed through a rotatory drier to ensure adequate mixing.When dry the product is of markedly improved resistance to caking.

Example 7 Ammonium nitrate in an edge-runner mill is treated with 0.5%of water containing of triamino tritolylmethan trisulphonate, ammoniumsalt, in solution. The dye is distributed during 20 minutes milling, andthe finely divided product, containing 20-30% of particles passing a zoomesh B. S. 8., sieve, which in the absence of the dye is liable to cakethat its use is severely restricted or even impossible in the explosiveart, now remains soft and friable for considerable periods aftermanufacture, even under unfavourable climatic conditions.

Example 8 Ammonium nitrate, in the form of granules 30-100 B. S. S.produced by a spray crystallization process, is treated with 0.1% of amixture of the sodium salts of the diand tri-sulphonates of dimethylrosaniline, known as Red Violet 4 R. S. (C. I. 694), applied fromaqueous solution. The product after drying is of unaltered particleform, but is remarkably resistant to caking.

Example 9 Ammonium nitrate is crystallized from aqueous solution withvigorous stirring, in the presence of 0.1% of the sodium salt of thetrisulphonate of monomethyl triamino diphenyl tolyl methane, so as togive very tiny crystals. These crystals, separated from their motherliquor, dried and repulverized are markedly resistant to caking.

Example 10 Ammonium nitrate in the form of a 95% aqueous solution at anelevated temperature is crystallized, in the presence of 0.05% of theammonium salt of the trisulphonate of ethyl rosaniline, known as RedViolet 5 R. S. (C. I. 693) in the saline solution, in a graining kettle,Fauser crystallizer, or similar apparatus, so that the heats ofcrystallization and transition of the ammonium nitrate serve toevaporate the contained Water. A dry product, markedly resistant tosetting when cold is obtained.

Iclaim:

1. Modified ammonium nitrate consisting of a mixture of 100 partsammonium nitrate and from .001 to 1.0 part of a soluble salt of apoly-sulphonated derivative of a dyestuff selected from the groupconsisting of diamino and triamino substituted triaryl methane dyestufisand lower N-alkyl mono to tetra substituted derivatives thereof, saidpoly-sulphonated derivative having a solubility of at least 0.5% in asaturated aqueous ammonium nitrate solution at 20 C., and which insolution in a saturated aqueous solution of ammonium nitrate conditionssaid solution to produce on crystallization in the temperature range inwhich the stable form of ammonium nitrate is ammonium nitrate IVcrystals of ammonium nitrate IV as [010] prisms, laths, plates orscales.

2. Ammonium nitrate as claimed in claim 1 wherein the dyestuff istri-sulphonated monomethyl triamino tritolylmethane, sodium salt.

3. A method for the production of modified ammonium nitrate whichcomprises incorporating into 100 parts of said ammonium nitrate from.001 to 1 part of a soluble salt of a poly-sul phonated derivative of adyestuff selected from the group consisting of diamino and triaminosubstituted triaryl methane dyestuffs and lower N-alkyl mono to tetrasubstituted derivatives thereof, said poly-sulphonated derivative havinga solubility of at least 0.5% in a saturated aqueous ammonium nitratesolution at 20 C. and which in solution in a saturated aqueous solutionof ammonium nitrate conditions said solution to produc oncrystallization in the temperature range in which the stable form ofammonium nitrate is ammonium nitrate IV crystals of ammonium nitrate IVas [010] prisms, laths, plates or scales.

i. A method for the production of ammonium nitrate as claimed in claim 3which comprises effecting direct crystallization of ammonium nitratefrom a solution containing at least one of the said dyestuffs.

5. A method for the production of ammonium nitrate as claimed in claim 3which comprises effecting granulation of aqueous solutions of ammoniumnitrate containing at least one of the aforesaid dyestuffs,

6. A method for the production of ammonium nitrate as claimed in claim 3which comprises adding 0.1 to 1.0 part of at least one of the afore saiddyestuffs by dry admixture to parts of spray crystallized ammoniumnitrate.

7. A method for the production of ammonium nitrate as claimed in claim 3which comprises spray crystailizing ammonium nitrate from theconcentrated aqueous solution, and wetting the granules thus formedafter solidification and before drying with an aqueous solution of atleast one or the said dyestuffs.

8. A method as claimed in claim 3 which comprises treating ammoniumnitrate with a solution of at least one of said dyestuffs in liquidammonia and subsequently evaporating the liquid ammonia.

9. A process as claimed in claim 3 which comprises treating ammoniumnitrate with a solution of at least one of said dyestuffs in a mixtureof ammonium nitrate and liquid ammonia, and subsequently evaporating theliquid ammonia.

10. A process as claimed in claim 3 which comprises applying to ammoniumnitrate at least one of said dyestufis absorbed in an absorbentmaterial.

11. A method as claimed in claim 10 wherein the absorbing material iskieselguhr.

12. Ammonium nitrate as claimed in claim 1 wherein the dyestuff istri-sulphonated pararosaniline ammonium salt.

13. Ammonium nitrate as claimed in claim 1 wherein the dyestuff istrisulphonated rosaniline ammonium salt.

14. Ammonium nitrate as claimed in claim 1 wherein the dyestufi istrisulphonated pp p triamino tritolyl methane ammonium salt.

15. Ammonium nitrate as claimed in claim 1 wherein the dyestuff is amixture of the sodium salts of diand tri-sulphonic acids of N-ethylrosaniline.

JOHN WI-IE'IS'I'ONE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,377,670 Burdett June 5, 19452,383,763 Bloch et a1. Aug. 28, 1945

1. MODIFIED AMMONIUM NITRATE CONSISTING OF A MIXTURE OF 100 PARTSAMMONIUM NITRATE AND FROM .001 TO 1.0 PART OF A SOLUBLE SALT OF APOLY-SULPHONATED DERIVATIVE OF A DYESTUFF SELECTED FROM THE GROUPCONSISTING OF DIAMINO AND TRIAMINO SUBSTITUTED TRIARYL METHANE DYESTUFFSAND LOWER N-ALKYL MONO TO TETRA SUBSTITUTED DERIVATIVES THEREOF, SAIDPOLY-SULPHONATED DERIVATIVE HAVING A SOLUBILITY OF AT LEAST 0.5% IN ASATURATED AQUEOUS AMMONIUM NITRATE SOLUTION AT 20* C., AND WHICH INSOLUTION IN A SATURATED AQUEOSU SOLUTION OF AMMONIUM NITRATE CONDITIONSSAID SOLUTION TO PRODUCE ON CRYSTALLIZATION IN THE TEMPERATURE RANGE INWHICH THE STABLE FORM OF AMMONIUM NITRATE IS AMMONIUM NITRATE IVCRYSTALS OF AMMONIUM NITRATE IV AS (010) PRISMS, LATHS, PLATES ORSCALES.